The present invention relates to a video decoder design and a video encoder design, and more particularly, to a residual up-sampling apparatus for performing transform block up-sampling in a video encoder/decoder and a residual down-sampling apparatus for performing transform block down-sampling in a video encoder.
The conventional video coding standards generally adopt a block based coding technique to exploit spatial and temporal redundancy. For example, the basic approach is to divide the whole source frame into a plurality of blocks, perform prediction on each block, transform residuals of each block, and perform quantization, scan and entropy encoding. Besides, a reconstructed frame is generated in an internal decoding loop of the video encoder to provide reference pixel data used for coding following blocks. For example, inverse scan, inverse quantization, and inverse transform may be included in the internal decoding loop of the video encoder to recover residuals of each block that will be added to predicted samples of each block for generating a reconstructed frame. The functions of the internal decoding loop of the video encoder are also implemented in a video decoder for recovering residuals of each block and generating a reconstructed frame.
For certain video coding standards, residual down-sampling of transform blocks and residual up-sampling of transform blocks may be implemented in a video encoder, and residual up-sampling of transform blocks may be implemented in a video decoder. There is a need for innovative residual down-sampling design and residual up-sampling design with low cost and/or high performance.